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15 Reasons a DuroMax Generator Won’t Start (Troubleshoot)

When your generator won’t start, chances are it’s at a time when it’s your only power source. I’ve put together this list to help you troubleshoot your starting problem.

A DuroMax generator won’t start due to a dirty carburetor, plugged fuel filter, plugged fuel tank vent, bad spark plug, plugged air filter, wrong choke setting, low engine oil, or old fuel.

Look for a bad starter solenoid, weak battery, or bad ignition switch on DuroMax generators with an electric start.

Keep reading for more causes of your starting problem. Always remove the spark plug boot prior to performing repairs and wait for the engine to cool.

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

This is Why Your DuroMax Generator Won’t Start

1. Empty Fuel Tank

Don’t overlook checking the fuel tank. You may have developed a fuel leak or the fuel gauge may be faulty causing you to run out of fuel before you thought you would.

SOLUTION: Check for a fuel leak or fuel gauge failure. Fix or replace faulty parts. Add fresh fuel to the fuel tank.

2. Old Fuel

You may not realize that gas can begin to break down and become less effective as soon as 30 days after purchase. Not only does it begin to break down, but ethanol found in most gas also attracts moisture to the fuel system.

The ethanol and moisture it attracts leave behind varnish and gummy deposits that can cause component failures and fuel restrictions. Water and ethanol will separate from gas and sink to the bottom of the tank.

Tips for purchasing and storing gas for a DuroMax generator:

  • Purchase fresh fuel with a minimum 87 octane rating (91 RON).
  • Never use gas with more than a 10% ethanol content. Low ethanol and ethanol-free fuel are best.
  • Consume fuel within 30 days.
  • Use a fuel stabilizer to keep gas stable longer.
  • Store fuel in an approved fuel container away from moisture or combustible products.

SOLUTION: Drain old gas from the generator. A fuel siphon pump works well for this. Mix fresh gas with a fuel additive in a fuel can. Add this mixture to the fuel tank.

Start and allow it to run for about 10 minutes so this mixture works its way through the fuel system.

I like a product called Sea Foam Motor Treatment. I use this product in every tank of gas to help reduce the issues that can result from using fuel with ethanol.

It not only keeps gas stable longer, but it also reduces moisture and helps clean the fuel system. Another good option is STA-BIL.

3. Clogged Fuel Filter

Check the fuel filter on the generator. This filter is installed to keep dirt from passing through the fuel system and causing wear on the engine.

When the filter isn’t regularly replaced, it can become so clogged with dirt and deposits that a good flow of fuel isn’t able to pass through the filter. This lack of fuel will cause the generator not to start.

For the average homeowner, I recommend replacing the fuel filter annually. You may have to replace it more often if you run the DuroMax generator regularly.

SOLUTION: Replace a plugged DuroMax fuel filter. You may find an easily accessible inline filter installed between the fuel lines.

However, on most DuroMax generators, the filter isn’t easy to locate. It may be installed at the bottom of the fuel tank or inserted into another fuel component.

4. Clogged Fuel Line

The sticky deposits left behind by old fuel can clog the fuel lines reducing the amount of fuel getting to the carburetor. Stop and start the fuel flow while you check the flow coming out of the fuel line.

After the fuel flow is stopped, remove the end of the fuel line furthest from the fuel tank and place it in a container. Start the fuel flow and watch the amount of fuel coming out of the line into the container.

Note: the container must be placed lower than the fuel tank because fuel cannot run uphill without the assistance of a pump.

SOLUTION: If you find a restriction in the fuel line, turn off the fuel flow, and remove the line from the generator. Spray carburetor cleaner to loosen the clog and blow compressed air to the line to remove it.

If you are unable to remove the fuel restriction or you find the line is dry or cracked replace it with a new fuel line of the same diameter and length.

5. Bad Carburetor

A carburetor is used on the generator to regulate the amount of gas that is mixed with air for combustion. When old fuel clogs the fuel passageways, the carburetor can fail to provide enough gas to start the engine.

Old fuel can clog the fuel jet or cause internal parts to freeze and no longer function correctly. The carburetor will have to be cleaned and damaged parts will have to be replaced to get it working again.

Before you start tearing apart the carburetor to clean it, make sure you are getting sufficient fuel to the carburetor. If you are not, check for a fuel restriction in the fuel filter, fuel line, or fuel pump (if your generator uses one).

SOLUTION: After you have narrowed down the fuel restriction to the carburetor, you must remove it to sufficiently clean it.

I know there are several sources that say you can clean it while installed, but you can’t get it truly clean without disassembling it to remove as much buildup as possible.

It helps to take photos while you take it apart so you can refer to them for reassembly.

Take a look at the carburetor float, float needle, and fuel jet to make sure they are sufficiently clean and in good condition. If you find any damaged parts, you must replace them using a carburetor rebuild kit or a replacement carburetor.

6. Plugged Air Filter

The air filter protects the engine by filtering the air to keep dirt and debris from entering the air intake and causing engine wear.

While the air filter is designed to protect the air filter, it can do damage if it isn’t kept clean and in good condition. An air filter can become so plugged with dirt without proper maintenance that sufficient air isn’t getting to the engine.

This not only can cause your starting problem, but it can cause the engine to overheat when you run the generator with a bad air filter.

SOLUTION: If you find the DuroMax air filter is very dirty or damaged, replace it with a new air filter. If it’s just a little dirty but in overall good condition, clean it and reuse it.

Because DuroMax uses a variety of types of air filters for different generator models, refer to your operator’s manual for cleaning instructions for your type of air filter. I

have included cleaning instructions for the most common types of filters run on a DuroMax below.

How to Clean a FOAM DuroMax Air Filter

  • Remove the air filter cover.
  • Remove the foam air filter.
  • Wipe to remove any dirt or debris left in the air filter housing or cover. Don’t allow dirt to fall into the air intake.
  • Inspect the air filter for damage. If it is brittle or has tears in it, replace it with a new air filter.
  • If the filter is in good condition, proceed with cleaning it.
  • Wash the filter using a mild dish detergent and water.
  • Rinse until the water runs clear and squeeze the filter to remove excess water.
  • Allow the filter to completely dry.
  • Lightly saturate the filter in clean engine oil. Squeeze the filter to remove excess oil.
  • Install the clean air filter into the air filter housing and install the air filter cover.

How to Clean a PAPER DuroMax Air Filter

  • Remove the air filter cover.
  • Remove the paper air filter.
  • Wipe to remove any dirt or debris left in the air filter housing or cover. Don’t allow dirt to fall into the air intake.
  • Tap the air filter element against a solid surface to loosen dirt and allow it to fall to the ground.
  • If the filter is very dirty, covered in oil, or damaged, you must replace the filter with a new one.
  • If it is in good condition, you can go ahead and use it.
  • Install the good filter into the air filter house and install the air filter cover.

7. Plugged Fuel Tank Vent

The fuel tank must be able to vent. DuroMax generators either vent the fuel tank through the fuel cap or a rollover vent is installed on the top of the fuel tank. This allows air to pass into the tank.

Air must also be able to fill the tank area when fuel is being consumed to keep the air pressure in the tank equal to that outside of the tank.

When air isn’t allowed to pass through the gas cap due to a plugged vent, the fuel tank will form a vacuum. This prevents fuel from getting to the carburetor and your generator will fail to start.

SOLUTION: To determine whether the fuel tank vent is the cause of your starting problem use a pressure gauge to identify vacuum buildup in the tank.

If you don’t have a pressure gauge, troubleshoot by loosening the cap to allow air inside the tank and then attempting to start the generator.

If the engine starts but stops running again after you tighten the gas cap and allow it to run for a while, you may have a problem with the cap. I recommend replacing the bad fuel tank vent.

8. Plugged Spark Arrestor

The spark arrestor screen is a metal piece on the muffler that prevents sparks and hot material from emitting from the DuroMax muffler. This screen is required to prevent injuries and fires.

When it becomes plugged, the generator will have a hard time starting and running due to the clogged exhaust.

SOLUTION: Remove the spark arrestor screen from the muffler. Take a look at it to ensure it isn’t torn and doesn’t have any holes in the screen. If it does, the screen must be replaced with a new one.

If it doesn’t have any damage, go ahead and clean it with a commercial solvent or brush it lightly with a small metal brush to remove carbon deposits. Once clean, reinsert the screen.

9. Bad Spark Plug

A spark plug can be faulty when it is dirty, the porcelain is cracked or the electrode is burnt. This will cause a DuroMax generator not to start because of a lack of spark.

SOLUTION: You can clean the spark plug to remove the deposits on the tip. If your spark plug tip is very dark in color or damaged, you must replace it with a new one.

The spark plug needs to be properly gapped following the manufacturer’s specifications as found in the operator’s manual. Starting problems can be caused by a spark plug that is gapped incorrectly or a spark plug wire that is loose.

10. Incorrect Engine Oil Level

A DuroMax generator may have a low engine oil sensor that will shut off the generator and not allow it to start. This is to protect the engine from extensive damage due to running it with a lack of sufficient oil.

If your generator doesn’t have a low engine sensor and has been run low on oil, it may no longer start because of damage.

Oil provides the lubrication needed for the internal engine parts to move freely. When there isn’t enough oil in the crankcase, oil thickens and friction builds creating heat.

SOLUTION: Check the engine oil level by placing the generator on a flat-level surface.

  • Remove the oil fill cap and wipe off the dipstick with a clean cloth to remove the oil.
  • Reinsert the dipstick into the oil-fill tube, but don’t screw on the cap.
  • Remove it and look at the oil level on the dipstick. Ensure it is in the full range on the dipstick.
  • If it is not at the correct level, correct the engine oil level by removing or adding a little oil.

When you find you have the correct engine oil level and the low oil sensor stays on, you may have a faulty sensor. It’s best to take the generator to a service center to be repaired.

If your DuroMax generator doesn’t have a low oil sensor or the sensor failed and you find the oil is low and it won’t start after correcting it, you may have caused engine damage.

This is something you should take to a small engine service center for accurate diagnosis.

11. Incorrect Choke Setting or Stuck Choke

The choke is required to restrict airflow to start a cold engine on a DuroMax generator or it won’t start.

Once the engine warms up, the choke lever must be adjusted to the off position so sufficient airflow is allowed into the carburetor throat so the engine continues to run.

When the choke is placed in the correct position and you continue to have airflow problems, check the choke linkage to make sure it is not stuck and is opening and closing correctly.

SOLUTION: Make sure the choke lever is in the correct position when starting a cold or warm engine. If you find the choke is stuck, use carburetor cleaner to help free it up so it moves without sticking.

12. Bad Recoil on a Manual Start Generator

When the starter recoil wears or parts of the recoil break, it’s hard or impossible to get the generator started. The rope on the recoil can become unstrung or the pulley, springs, or clips may break causing your starting problems.

SOLUTION: Sometimes, restringing the recoil is all you need. Other times you will have to replace broken parts in your recoil. Before replacing parts, price out a full recoil replacement.

Depending on the price difference, it may be better to replace the recoil assembly over tearing it down and replacing broken components.

13. Bad Battery (Electric Start)

Make sure the battery is charged. If it has a low charge, you can attempt to charge the battery. If it won’t hold a charge, it’s time to replace the battery with a new one.

Check the cables and wiring to make sure you have good continuity and making good connections.

SOLUTION: Check the voltage of the battery and charge it if it is weak. Replace a dead battery or one that won’t hold a charge.

14. Bad Ignition Switch (Electric Start)

The switch can go bad on a generator with an electric start preventing it from starting.

SOLUTION: Test the switch using a multimeter and replace it if necessary.

15. Bad Starter Solenoid (Electric Start)

You may hear a clicking or humming sound when you press the ignition switch button or turn the key (depending on your model) and your generator won’t start. Or, you may find the wiring is getting hot and beginning to smoke.

These are indications the solenoid may be bad. A starter solenoid goes bad when the internal spring gets weak or the copper plate begins to corrode.

A weak starter, bad battery, or bad ground can also be the reason for the solenoid failure.

SOLUTION: You can attempt to bypass the starter using a screwdriver or pliers by touching the cable from the battery and the cable to the starter. Be careful as it may throw a spark.

If the engine turns over with the solenoid bypassed, it is likely the starter solenoid is bad.

You must check for loose wires or bad ground before replacing the solenoid. These are items that can cause the solenoid to not work correctly.

The good news is most portable DuroMax generators with an electric start have a manual starter recoil installed to pull-start it to get it running. If you are able to manually start it, you can narrow down your problem to the electric start system.